on a whim I searched " "at" command" at dev tracker (https://dev.getsol.us/T6799).
It was requested in 2018 and rejected because it hadn't been updated since '16----our own Lead in that thread suggested Dcron as the better alternative.
Since we are dealing with 4-year-old info above, then it's possible all my typing is nonsense. If you feel you've reached this message in error, try requesting it here https://dev.getsol.us/; note "request a package" button upper left on this page.
edit: I did not see this package at flatpak or snap either